unable to tune free buffer waits

list,
picking up the thread from my previous post......(7.3.2 on AIX)

• doing a select count(*) on a 5 million table is taking 5-6 hours !! ** multiblock_read_count is 16 (max for the platform)

db_writers = 4 (async_Io is false)
db buffers are 80MB

i have checked the statistics by using event 10046 and also by looking at session_event

both show "free buffer waits" and the table is being read SEQUENTIALLY many times
!! (FTS should be done using SCATTERED READS )

even when doing scattered reads, the blocks read are 4 or 5 at a time...(not 16)

other issues

• i did a count(*) on ANOTHER table (right after importing 4 million rows) and all was ok
• this table is heayly inserted into and i did the count(*) AFTER the insertion was finished.
• alter system checkpoint takes 40 min. !!

what's going on ??

TIA
Rahul

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Author: Rahul
  INET: rahul_at_ratelindo.co.id

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